Characteristics of DNMT3A-R882 Mutation in AML

Introduction

Genetic mutations play an important role in the development and progression of acute myeloid leukemia (AML). One of the common aberration in AML is mutation in the epigenetic modifying gene, DNA methyltransferase 3α (DNMT3A). Despite the active investigations, the exact impact of mutation on the development of AML is not completely known. The occurrence of mutation in pre-leukemic cells explains a particular attention to DNMT3A. The most common mutation is located in codon R882 (DNMT3A^R882mut). The objective of this study is to compare clinical and prognostic characteristics of AML patients in relation to presence of DNMT3A^R882mut. The quantification of the mutation burden in follow up samples was performed both after standard therapy and after allogeneic stem cell transplantation (alloSCT). In addition, it was investigated whether the quantification of the mutational burden of DNMT3A^R882mut is significant to the progression of disease.

Methods

Samples of 580 AML were retrospective analyzed using HRM-PCR, capillare electrophorese, and Sanger Sequencing. The median observation period was 495 days. Of 580, 69 have DNMT3A^R882mut. Mutation burden was evaluated in follow-up samples by quantitative PCR. The statistical methods were selected according to sample distribution and evaluated with SPSS (significance level p <0.05).

Results

DNMT3A^R882mut were associated with a higher level of leukocytes and blasts at diagnosis, with M4-M5 variant of AML, and with normal karyotype. It was found that NPM1 and FLT3-ITD are more frequent co-mutations that have a significant effect on the prognosis of disease. Analysis of mutation burden of DNMT3A^R882mut at diagnosis showed a large spread (0.02 - 66.9 %). At the time of diagnosis, DNMT3A^R882mut transcript levels did not correlate with clinical and prognostic characteristics. The mutation burden decreased after therapy, but was always visible in CR after standard therapy. In CR after allogeneic stem cell transplantation (alloSCT) with complete donor chimerism mutation was not detected. In relapse of AML, an increasing of the mutation burden were found in all patients, both after therapy, and after alloSCT. In relapse samples, the same mutant clone was found.

Conclusion

The DNMT3A mutation is a common genetic aberration in AML patients, which is associated with specific clinical and prognostic data. The presence of co-mutations, especially NPM1 and FLT3-ITD, has a significant effect on the prognosis of patients.

Quantitative detection of DNMT3A^R882mut at different time points of disease revealed the persistence of mutated clone after standard therapy and disappearance of DNMT3A^R882mut after alloSCT. It is suggest that alloSCT is the optimal treatment option for the eradication of DNMT3A^R882mut in AML patients.